On Monday 17 November 2025 16:18:14 Martin Storsjö wrote:
> On Sat, 25 Oct 2025, Pali Rohár wrote:
>
> > ---
> > mingw-w64-crt/testcases/t_time.c | 96 ++++++++++++++++++++++++++++++--
> > 1 file changed, 92 insertions(+), 4 deletions(-)
> >
> > diff --git a/mingw-w64-crt/testcases/t_time.c
> > b/mingw-w64-crt/testcases/t_time.c
> > index 50b07d0083a7..75a15d816d31 100644
> > --- a/mingw-w64-crt/testcases/t_time.c
> > +++ b/mingw-w64-crt/testcases/t_time.c
> > @@ -10,14 +10,17 @@ int __cdecl ftime64(struct __timeb64 *tb64);
> >
> > int main()
> > {
> > - time_t t;
> > - __time32_t t32;
> > - __time64_t t64;
> > + time_t t, t_;
> > + __time32_t t32, t32_;
> > + __time64_t t64, t64_;
> > struct timeb tb;
> > struct _timeb tb_;
> > struct __timeb32 tb32;
> > struct __timeb64 tb64;
> > struct tm *htm;
> > + struct tm tm1;
> > + struct tm tm2;
> > + struct tm tm3;
> > int ret1, ret2, ret3;
> > const char *str;
> > const wchar_t *wstr;
> > @@ -95,7 +98,49 @@ int main()
> > assert (htm->tm_yday == 74);
> > assert (htm->tm_isdst == 0);
> >
> > - /* ctime returns time string in local timezone, so set local timezone to
> > UTC to have test timezone independent */
> > + time_t times[] = {
> > + 1700000000 /* Tue Nov 14 22:13:20 UTC 2023 */,
> > + 1600000000 /* Sun Sep 13 12:26:40 UTC 2020 */,
> > + };
> > + for (size_t i = 0; i < sizeof(times)/sizeof(*times); i++) {
> > + t = times[i];
> > + htm = localtime (&t);
> > + tm1 = *htm;
> > + printf ("localtime(%lld): sec=%d min=%d hour=%d mday=%d mon=%d
> > year=%d wday=%d yday=%d isdst=%d\n",
> > + (long long)t, htm->tm_sec, htm->tm_min, htm->tm_hour,
> > htm->tm_mday, htm->tm_mon, htm->tm_year, htm->tm_wday, htm->tm_yday,
> > htm->tm_isdst);
> > + t_ = mktime (htm);
> > + printf ("mktime(): %lld sec=%d min=%d hour=%d mday=%d mon=%d
> > year=%d wday=%d yday=%d isdst=%d\n",
> > + (long long)t_, htm->tm_sec, htm->tm_min, htm->tm_hour,
> > htm->tm_mday, htm->tm_mon, htm->tm_year, htm->tm_wday, htm->tm_yday,
> > htm->tm_isdst);
> > + assert (t_ == t);
> > + assert (memcmp (htm, &tm1, sizeof(tm1)) == 0);
> > +
> > + t32 = t;
> > + htm = _localtime32 (&t32);
> > + tm2 = *htm;
> > + printf ("_localtime32(%d): sec=%d min=%d hour=%d mday=%d mon=%d
> > year=%d wday=%d yday=%d isdst=%d\n",
> > + t32, htm->tm_sec, htm->tm_min, htm->tm_hour, htm->tm_mday,
> > htm->tm_mon, htm->tm_year, htm->tm_wday, htm->tm_yday, htm->tm_isdst);
> > + t32_ = _mktime32 (htm);
> > + printf ("_mktime32(): %d sec=%d min=%d hour=%d mday=%d mon=%d
> > year=%d wday=%d yday=%d isdst=%d\n",
> > + t32_, htm->tm_sec, htm->tm_min, htm->tm_hour, htm->tm_mday,
> > htm->tm_mon, htm->tm_year, htm->tm_wday, htm->tm_yday, htm->tm_isdst);
> > + assert (t32_ == t32);
> > + assert (memcmp (htm, &tm2, sizeof(tm2)) == 0);
> > +
> > + t64 = t;
> > + htm = _localtime64 (&t64);
> > + tm3 = *htm;
> > + printf ("_localtime64(%lld): sec=%d min=%d hour=%d mday=%d mon=%d
> > year=%d wday=%d yday=%d isdst=%d\n",
> > + t64, htm->tm_sec, htm->tm_min, htm->tm_hour, htm->tm_mday,
> > htm->tm_mon, htm->tm_year, htm->tm_wday, htm->tm_yday, htm->tm_isdst);
> > + t64_ = _mktime64 (htm);
> > + printf ("_mktime64(): %lld sec=%d min=%d hour=%d mday=%d mon=%d
> > year=%d wday=%d yday=%d isdst=%d\n",
> > + t64_, htm->tm_sec, htm->tm_min, htm->tm_hour, htm->tm_mday,
> > htm->tm_mon, htm->tm_year, htm->tm_wday, htm->tm_yday, htm->tm_isdst);
> > + assert (t64_ == t64);
> > + assert (memcmp (htm, &tm3, sizeof(tm3)) == 0);
> > +
> > + assert (memcmp (&tm1, &tm2, sizeof(tm1)) == 0);
> > + assert (memcmp (&tm2, &tm3, sizeof(tm2)) == 0);
> > + }
> > +
> > + /* ctime, localtime and mktime returns time string in local timezone, so
> > set local timezone to UTC to have test timezone independent */
> > putenv ("TZ=UTC");
>
> In addition to setting TZ=UTC here, is it possible to set some other
> well-known timezone that would be available everywhere, which we could use
> for some testcases for cases closer to the DST switchover time? We could do
> that for both mktime and localtime IMO.
I could try to add, but I'm not sure if CRT libraries would be able to
process DST support for non-system timezone. Because Windows system and
WinAPI has just one fixed timezone, which provides bunch of timezone and
DST related functions. And CRT library allows to define any timeshift,
so then there can be a mix of WinAPI timezone, CRT timezone, WinAPI DST
and CRT DST... That is why I wrote test below the quoted part in UTC as
it does not have any DST and no offset.
> In itself, these test additions probably are fine though - the above would
> be nice extras. But given that corner case handling close to DST
> switchovers, I think it would be good to actually check such a case.
>
> So this patchset in itself looks ok, except for the one issue I found in
> 2/7.
>
> // Martin
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